I'm running the Mint Cinnamon 19 beta. This printer and scanner worked great in Mint 18, but I did fresh install this week and now can't get it to scan. I've downloaded fresh driver/install packages from Brother, and followed the instructions here:https://sites.google.com/site/easylinuxtipsproject/15

Previously this seemed to work fine. I've gone through it a couple of times with no success. I suspect I'm missing something obvious. My best clue is that scanimage -L finds nothing. sane-find-scanner doesn't find the scanner, but sudo sane-find-scanner does.

barry@barry-desktop:~$ sudo scanimage -L
[sudo] password for barry:
No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).
barry@barry-desktop:~$ sane-find-scanner
# sane-find-scanner will now attempt to detect your scanner. If the
# result is different from what you expected, first make sure your
# scanner is powered up and properly connected to your computer.
# No SCSI scanners found. If you expected something different, make sure that
# you have loaded a kernel SCSI driver for your SCSI adapter.
could not open USB device 0x1d6b/0x0002 at 002:001: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0001 at 004:001: Access denied (insufficient permissions)
found USB scanner (vendor=0x04f9, product=0x01a6) at libusb:001:005
could not open USB device 0x046d/0x082b at 001:004: Access denied (insufficient permissions)
could not open USB device 0x05e3/0x0605 at 001:002: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0002 at 001:001: Access denied (insufficient permissions)
could not open USB device 0x1bcf/0x0007 at 003:002: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0001 at 003:001: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0003 at 006:001: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0002 at 005:001: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0003 at 008:001: Access denied (insufficient permissions)
could not open USB device 0x045e/0x07f8 at 007:002: Access denied (insufficient permissions)
could not open USB device 0x1d6b/0x0002 at 007:001: Access denied (insufficient permissions)
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.
# Not checking for parallel port scanners.
# Most Scanners connected to the parallel port or other proprietary ports
# can't be detected by this program.
# You may want to run this program as root to find all devices. Once you
# found the scanner devices, be sure to adjust access permissions as
# necessary.
barry@barry-desktop:~$ sudo sane-find-scanner
# sane-find-scanner will now attempt to detect your scanner. If the
# result is different from what you expected, first make sure your
# scanner is powered up and properly connected to your computer.
# No SCSI scanners found. If you expected something different, make sure that
# you have loaded a kernel SCSI driver for your SCSI adapter.
found USB scanner (vendor=0x04f9, product=0x01a6) at libusb:001:005
# Your USB scanner was (probably) detected. It may or may not be supported by
# SANE. Try scanimage -L and read the backend's manpage.
# Not checking for parallel port scanners.
# Most Scanners connected to the parallel port or other proprietary ports
# can't be detected by this program.
barry@barry-desktop:~$ sudo usermod -a -G scanner barry
barry@barry-desktop:~$ groups
barry adm cdrom sudo dip plugdev lpadmin scanner sambashare
barry@barry-desktop:~$ sudo scanimage -L
No scanners were identified. If you were expecting something different,
check that the scanner is plugged in, turned on and detected by the
sane-find-scanner tool (if appropriate). Please read the documentation
which came with this software (README, FAQ, manpages).

And here's the contents of xed admin:///lib/udev/rules.d/60-libsane1.rules

I've just been through the same issues on mate with mfc8840d networked
after much fuss and bother this is what i did. Your mileage may vary, and please mote this is my scanner and you must change files accordingly
I installed xsane as the scanner gui
I also installed ,previously, the printer scanner software as per brothers website.
Printer works fine but Xsane said that it could not find a device.
so:
get the driver for your scanner here:http://support.brother.com/g/s/id/linux ... edirect=on
I followed the instructions ,
For my printer i use brsaneconfig, so changed the commands accordingly.
so here is what i typed into cli directly as root: (note that the model name must be exact. I ended up doing a copy of such from brother)